NEW ORLEANS — Candidates started signing up Wednesday to challenge Mayor Ray Nagin in an election likely to focus on the incumbent’s handling of city efforts to rebuild after Hurricane Katrina.

About a dozen candidates have said they’ll run against Nagin, including two who filed papers within an hour of the opening of qualifying Wednesday.

One was former minor-league baseball team owner Rob Couhig, who filed one of three lawsuits earlier this year to keep the city from postponing the election because of the hurricane destruction. Originally scheduled for February, the election is now set for April 22.

“The most important thing is that we have a real intelligent discussion about the future,” Couhig said. “It’s frustrating to me that it’s six months after the storm and we’re still waiting for leadership and to rebuild.”

Also filing papers Wednesday morning was political newcomer Norbert Rome.

Politics of KatrinaNagin was popular before Hurricane Katrina struck the city on Aug. 29. Since then, he has struggled with overwhelmed and underfunded infrastructure, well publicized gaffes and allegations that he did too little to evacuate the city before the storm.

Video: New Katrina poll
Several of his expected challengers, including Louisiana Lt. Gov. Mitch Landrieu, were one-time Nagin allies.

To win, a candidate must get a majority of the votes. If that doesn’t happen in April, the top two finishers will face off on May 20.

Candidates must file by the close of business Friday and pay a fee to be on the ballot.

The storm damage forced most residents to evacuate and roughly 300,000 of the city’s nearly 500,000 pre-Katrina residents remain scattered.

Some advocates had hoped to postpone the election further, saying more should be done to ensure the city’s black population can participate.

More than two-thirds of pre-Katrina New Orleans was black. Some of the most devastated neighborhoods, including the Ninth Ward and eastern New Orleans, were primarily black, and those neighborhoods remain largely abandoned.